Mark Scheme for the AQA Biology 1411 Jan 2010 exam

7/30/2019 Mark Scheme for the AQA Biology 1411 Jan 2010 exam

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Version 1.0: 0909

klmGeneral Certificate of Education

Biology 1411

BIOL4 Populations and Environment

Mark Scheme

2010 examination - January series


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Mark schemes are prepared by the Principal Examiner and considered, together with therelevant questions, by a panel of subject teachers. This mark scheme includes any

amendments made at the standardisation meeting attended by all examiners and is the schemewhich was used by them in this examination. The standardisation meeting ensures that the

mark scheme covers the candidates responses to questions and that every examinerunderstands and applies it in the same correct way. As preparation for the standardisation

meeting each examiner analyses a number of candidates scripts: alternative answers notalready covered by the mark scheme are discussed at the meeting and legislated for. If, after

this meeting, examiners encounter unusual answers which have not been discussed at themeeting they are required to refer these to the Principal Examiner.

It must be stressed that a mark scheme is a working document, in many cases further

developed and expanded on the basis of candidates reactions to a particular paper.Assumptions about future mark schemes on the basis of one years document should be

avoided; whilst the guiding principles of assessment remain constant, details will change,depending on the content of a particular examination paper.


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Biology - AQA GCE Mark Scheme 2010 January series

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Question Part Marking Guidance Mark Comments

1 (a) Small surface area to volume ratio / more fat;

Lose less heat (to the environment) / for insulation;

When they are sitting on eggs;

2 max

1 (b)(i) The further north/higher the latitude, the higher the percentage (ofwhite snow geese);

1

1 (b)(ii) Snow lying longer/melts slower further north/at greater latitudes;

White geese better camouflaged (further north);

Predation linked to survival/reproductive success;

3 Q In order to gain the last marking

point, candidates must explain howsurvival or reproductive success isaffected.

1 (c) Snow melts earlier/snow melts further north / less snow;

White geese decreasing as less well camouflaged/atdisadvantage/blue geese increasing as better camouflaged/at an

advantage;

2

1 (d)(i) Stabilising; 1 Do not accept stable

1 (d)(ii) Few geese survive at the extremes/most survive from the middleof the range;

1


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4


2 (a) Extracellular digestion / releases enzymes;

Starch to monosaccharides /glucose/sugars/smaller molecules ;

Respire product of digestion;

Produce carbon dioxide from respiration;

2 max

2 (b) Correct answer of 40;;

Incorrect answer showing clearly that a difference in mass hasbeen divided by time;

2

2 (c) Lower as plants contain a lower proportion of nitrogen/higherproportion of carbon/ higher C:N ratio;

Nitrogen found (mainly) in protein/amino acids / nitrogen used to

make protein;

2


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2 (d) Investigation refers to a single species and other species might not

respond in the same way;

Investigation carried out in greenhouse where conditionscontrolled;

Accept any other valid answers relating to how an increase incarbon dioxide concentration might increase caterpillar damage,e.g.:

Caterpillars may eat more to compensate (for low nitrogen/protein);

Increased temperature (resulting from higher carbon dioxideconcentration will increase rate of growth /reduce generation time;

Other organisms interfere with results;

2 max Remember question concerns

caterpillar damage


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3 (a) All organisms of one species in a habitat/area/place/at one time; 1 Accept group

3 (b)(i) From curve C;

Find age as a percentage of a maximum/find value when5000/50% still alive;

(Use to) calculate as a percentage of 95/ Answer = 85 years;

3 Q This question tests quality ofwritten communication. Marks maybe awarded for calculating the answerbut this must be supported byadequate explanation making thepoints listed.

If curve A or B are given, figures forlast mark point areA 8B 50All three +/- 2

3 (b)(ii) More disease/poor food supplies/poor sanitation/poor medicalcare;

High death rate among the young/in childhood / curve dropssteeply at first/in first 40;

2 Overcrowding not enough

Ignore ref to years or percentage


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4 (a)(i) Method of positioning quadrats,E.g. Find direction and distance from specified point/

find coordinates on a grid / split area into squares;

Method of generating random numbers;E.g. From calculator/telephone directory/numbers drawn from a

hat;

2 Last point represents minimumanswer

Q Do not credit any method that relieson throwing a quadrat

4 (a)(ii) Calculate running mean/description of running mean;

When enough quadrats, this shows little change/levels out (ifplotted as a graph);

Enough to carry out a statistical test;

A large number to make sure results are reliable;

Need to make sure work can be carried out in the time available;

2 max

Ignore terms that are not incorrectRegards large numbers as 10/10% +

4 (b) Coppice different parts of the wood at different times;

As data show many daffodils flowering 4/5 years after coppicing;

2 Q Second point needs specificreference to the graph, numbers andtime after coppicing. Accept anycorrect answer that does this.

4 (c) Positive correlation between rainfall and flowering/the higher therainfall, the more daffodil flowers;

Negative correlation/the higher the temperature the fewer daffodilsin flower;

All statistically significant so not likely to be/not due to chance;

2 max


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5 (a) Krebs cycle/link reaction/pyruvate to acetylcoenzyme A; 1 Q Accept valid alternative for any ofthese steps.

5 (b) (Respiratory reactions controlled by) enzymes;

Rate decreases as less kinetic energy/fewer collisions (betweensubstrate and active site) fewer E-S complexes formed;

2

5 (c) Requires hydrogen/electrons / is reduction;

Hydrogens from reduced NAD/reduced NAD reduces (pyruvicacid) / reduced NAD oxidised;

2 Information may be on diagram

5 (d) Respiring anaerobically;

(Anaerobic respiration/respiration with nitrogen) lessefficient/produces less ATP;

More anaerobic respiration/ more glucose/substrate must berespired to produce same amount of ATP (so more carbon dioxideproduced);

3


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6 (a) Vegetation consists mainly of low growing species/herbs/annuals/no/few tress;

Species X has high rate of photosynthesis at high light intensity;

Species X grow fastest at high rate of photosynthesis / at high lightintensities;

Will outcompete other speciesY/Z;

3max

Do not credit Species X is first tree

6 (b) Produces shade/reduces light intensity;

Species Z grows best/photosynthesis best/ in low light intensity /Species Z does not grow well / low rate of photosynthesis in highlight intensity;

2

Accept answers in terms of CO2absorption


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7 (a)(i) Will work in all weather conditions/hairs will stick to it even ifshrew/animal is wet/ withstand rain;

1

7 (a)(ii) So shrews come into contact with glue; 1

7 (b) Avoids bias/allows statistical tests to be carried out; 1 Allow description

7 (c)(i) Increases the reliability of the measurements;

If measurements are repeatable, differences less likely to be dueto measurement/personal error/ anomalies unlikely;

2Accept advantages of repeatableresults. E.g. identifyinganomalies/remove errors

7 (c)(ii) Plot graph/scatter diagram of one set of results against the other;

Expect to see points lying close to line / Line should slopeupwards/show positive correlation;

OR

Plot measurement against hair number;

Look for overlying / corresponding points;

2 Q To gain first marking point,candidates must say what has beenplotted.

If what is being plotted is not clear,second point cannot be awarded.

7 (d)(i) One mark for a valid explanation based on individual shrewsentering more than one hair tube / many hairs from same shrew/shrews enter without leaving hair;

1

7 (d)(ii) Rules out differences due to changes in population / changes inenvironmental conditions;

That could be produced by births/deaths/migration/specificexample of environmental conditions affects results;

2


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7 (e) (A statistical test) determines the probability of results being due tochance;

Enables null hypothesis/description of null hypothesis to beaccepted/rejected;

Determines whether correlation/result is significant;

2 max

7 (f)(i) (Curve/line of best fit shows) positive correlation/ description ofpositive correlation;

1

7 (f)(ii) Curve/line of best fit (almost) parallel to x-axis/horizontal / level/ nocorrelation / index is independent of number of shrews;

Hair tubes with positive results when no shrews trapped;

Small size of shrews means shrews may not trigger traps;

2 max


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8 (a) 1 Light (energy) excites/raises energy level of electrons inchlorophyll;

2 Electrons pass down electron transfer chain;

3 (Electrons) reduce carriers/passage involves redoxreactions;

4 Electron transfer chain / role of chain associated withchloroplast membranes / in thylakoids / grana;

5 Energy released / carriers at decreasing energy levels;

6 ATP generated from ADP and phosphate/Pi /phosphorylation of ATP;

5 max QAccept any reasonable alternativefor electron transfer chain.

Example such as chemiosmosis;

8 (b) 1 Some light energy fails to strike/is reflected/not of

appropriate wavelength;

2 Efficiency of photosynthesis in plants is low/approximately2% efficient;

3 Respiratory loss / excretion / faeces / not eaten;

4 Loss as heat;

5 Efficiency of transfer to consumers greater than transfer toproducers/approximately 10%;

6 Efficiency lower in older animals/herbivores/ primaryconsumers/warm blooded animals/homoiotherms;

7 Carnivores use more of their food than herbivores;

6 max

Q Accept figures below 5%. Acceptfigures over 5% but below 10% ifclearly related to maximum efficiency.


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8 (c) 1 Slaughtered when still growing/before maturity/while youngso more energy transferred to biomass/tissue/production;

2 Fed on concentrate /controlled diet /controlledconditions/so higher proportion of (digested) foodabsorbed/lower proportion lost in faeces / valid reason foraddition;

3 Movement restricted so less respiratory loss / less energyused;

4 Kept inside/heating/shelter / confined so less heat loss / nopredators;

5 Genetically selected for high productivity;

4 max Q The principle here is one mark foridentifying a relevant point and

offering an explanation. Accept otherequivalent answers.

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Mark Scheme for the AQA Biology 1411 Jan 2010 exam

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